Critically, at low speed, this meant that a second sensor necessary to ensure redundancy—the accelerometer measuring g-forces at high speeds—was no longer applicable. The software would now fire on the basis of a single sensor, the angle-of-attack vane. And it would do so at low speeds, which usually meant when a plane was most vulnerable: at takeoff or landing. No one appears to have fully considered the human factors—how a failure in the single sensor would make the plane appear to go haywire at a time when pilots were already busy and dangerously close to the ground.
